Escape Velocity from a Black Hole's Gravity

[kingyof2thejring]

Homework Statement

A black hole has a mass of 2x10^31 kg What is the minimum radius from which a photon can escape its gravity?

Homework Equations

The Attempt at a Solution

does this equation give me the answer "gravitational radius" = (2Gm)/c^2

 

[moose]

Yes .
Google Schwarzschild radius
http://www.google.com/search?hl=en&q=Schwarzschild+radius&btnG=Google+Search

 

[kingyof2thejring]

cheers.....